Plaster-board



L. E. ARMSTRONG AND H. B. BHUUKUMBROUGH DLASTER BOARD.

APPLICATION men 00130, m9.

1,347,487. Patented July 27, 19,20

UNITED STATES PATENT OFFICE.

LOUIS E. ARMSTRONG AND HUGH BOWYER BROCKENBRQUGH, OF FORT DODGE, IOWA,

' .ASSIGTIORS TO PLYMOUTH GYPSUM COMPANY, OF FORT DODGE, IOWA, A COR-PO- nnrion or Iowan Specification of Letters Patent.

rriasrnanoaran.

Application filed October 30, 1919. Serial lq'o. 834,526.

To all whom it may concern.

Be it known that we, Louis E. ilnMs'rRoNo and linen l3. llrocunxcnouoii, both citi eons of the United States, and both residents of Fort Dod e, in the county of Webster and State of Iowa, have invented certain new and nsefullmprovements in Plaster-Board, of which the following is a speciiication.

This invention relates to improvements in plaster board and more particularly to a construct-ion for plaster board in which a novel method is employed for covering or binding the edges of the board to prevent breaking or roughening of the same in the handling of the boards. The nature of the material is such that it is more or less subject to damage, the plaster being fragile and the covering easily torn, hence the treatment of the edges promotes the preservation of the finished product to a large degree.

The novel features of the invention are herein fully set forthand illustrated in the accompanying drawings, in which-- Figure l is a view in perspective of a section'of plaster board, with portions displaced to show, the construction employed;

Fig. 2 is a view in cross-section of the plaster board taken on line 2, 2 of Fig. 1;

Fig. 3 is an enlarged detail view of the edge portion of a board illustrating the results sought to be obtained, and

Fig. 4e isa cross-sectional view of a modified construction embodying the features of the invention.

Plaster board is a term applied to an article of manufacture used in the covering of walls and ceilings of buildings and ordinarily consists of'a la er or layers of plaster interposed between sheets or coverings of fibrous material, such as paper or the like, the product being placed upon the market in the form of boards of suitable dimensions for convenient handling and transportation. The board to which the present invention relates consists of a body 1 of plaster of a desired thickness to the faces of which are applied coverings 2 and 3, for convenience hereinafter designated the bottom and top covering sheets respectively. Although the methods of manufacture may vary, a suit able method involves the application of a layer of plaster in its soft or plastic state upon the covering sheet 2, applying the top covering 3, and introducing the board between pressure rolls, thus effecting the adherence of the covering material to the body and the formation of a sheet or board of uniform thickness.

Referring now in detail to a preferable method for treating the edges of the board, the material of the body 1 is applied to the covering sheet 2 in a manner to provide the latter with a marginal portion i extending beyond the edge of the body 1. This marginal portion is adapted to be folded upwardly against the edge of the body to form an end covering with a sufficient amount beyond to provide a folding marginal por tion or flap 6 adapted to be folded over and down upon the opposite face of the body member. Prior to the folding down of the marginal portions 6 of the bottom sheet or covering 2, the top covering sheet 3'is applied, said top covering having its edges preferably terminating flush with the edges of the body 1. Along each margin of the top covering sheet 3, and especially adjacent the edges of the'body 1 covered by the marginal portions of the bottom covering sheet 2, there are provided a plurality 7 of apertures or perforations 7. arranged in any suitable manner, although preferably in two parallel rows, the perforations of each row. being in staggered relation. The

upper covering sheet thus applied to the body with the perforated margin in contact therewith, the margin 6 of the bottom sheet 2 is folded down upon and overlapping the perforated margin of the top covering sheet, the board being passed between the rolls during or immediately subsequent to the folding operation. The pressure thus applied produces the following resultsThe underlapping perforated margin of the top covering sheet 3 is pressed downwardly into 7 the plastic material of the body, and the' folded over margin 6 of the bottom covering is likewise pressed down so that it lies the perforations 1 and into contact with the under surface of the folded-over margin 6 of the bottom covering sheet 2. Normally the pressure thus applied will be sufficient to effect a' slight spreading of the plastic I material beyond the edges of the perforations, somewhat in the manner shown in Fig. 3.

When the body has become hardened in the drying process, the results obtained are substantially as follows: The material of the body thus forced through the perforations forms a series of integral rivet-like members 8 (Fig. 3). which adhere to the edges of the perforations and to the surface of the overlapping margin of the bottom covering sheet. Furthermore, the slight spreading of the material between the lapping margins of the sheets forms in effect a head 9 at the end of each member 8, which act to produce an anchoring effect between the body and the perforated margin of the top sheet, and in addition produces an increased surface of adhesion between the members 8 of the body and the overlapping margin of the bottom covering sheet. In this manner the margins of the covering sheet are secured or bound separately to the body 1, as well as cemented together,,thus providing a securely and permanently bound or sealed edge for the board.

In Fig. 4 is illustrated an obvious modification or departure from the construction herein set forth, wherein the bottom and top covering sheets are applied in the same manner as before described, but in this instance the folded-over margin 10 is first applied to the top face of the body 1 and the margin of the top covering overlaps said margin 10 of the bottom covering sheet In this case the perforations 11 are formed in the underlapping. margin, namely, the folded over margin 10 of said bottom sheet. The results accomplished are quite the same asbefore described.

Obviously other modifications may be introduced Without departing from the spirit of the invention, and therefore we do not wish to *be limited as to the scope of the invention except in so far as it is expressly set forth the appended claims.

We claim as our invention:

1. A plaster board comprising a body of plastic material, a sheet of fibrous material covering one face of said body and having a. marginal portion engaging an edge of said body and adapted to be folded over upon the opposite face of said body, a sheet of fibrous material covering the opposite face of said body and in lapping engagement having lappin with the folded-over marginal portion of said first-mentioned sheet, the latter having portions thereof removed to permit the material of the body to pass through said underlapping marginal portion and to adhere to said folded-over marginal portion.

2. A plaster board comprising a body of plastic material, a sheet of fibrous material covering one face of said body and having a marginal portion engaging an edge of said body and adapted to be folded over upon the opposite face thereof, a sheet of fibrous material covering the opposite face of said body and having lapping engagement with the folded-over marginal portion of said first-mentioned sheet, there being a plurality of apertures formed in the underlapping marginal portion.

3. A plaster board comprising a body of plastic material, a sheet of fibrous material covering one face of said body and having a marginal portion adapted to be folded to inclose an edge of said body and to overlie the opposite face thereof, a sheet of fibrous material covering said opposite face and 'engagement with the foldedover marginal portion of said first-mentioned sheet, the nnderlapping margin being perforated to permit the entrance of the material of the body therein and in contact with the overlappin margin.

4. A plaster board comprising a body of plastic material, a covering of'-'fibroi1s material inclosing said body, the marginal portions of said covering having lapping engagement on one face of said body, the underlapping marginal portion being provided with perforations permitting the entrance of the material of the body therein and in contact with the overlapping margi' nal portion.

5. A plaster board comprising a body of plastic material, a sheet of. fibrous material covering one face of said body and provided with a perforated marginal portion, a sheet of fibrous material covering the opposite face of the body and having a marginal portion engaging the edge of said body and folded over and upon the perforated marginal portion of said first-mentioned sheet.

In witness whereof, we hereunto subscribe our names this 25th day of Oct., A. 1)., 1919.

LOUIS E. ARMSTRONG.

' HUGH BOWYER BROCKENBROUGH. 

